Os conteúdos das glândulas metatorácicas de insetos adultos do percevejo Dichelops melacanthus (Hemiptera: Pentatomidae) foram analisados. Os compostos de defesa foram identificados combinando as técnicas de cromatografia gasosa (CG), cromatografia gasosa acoplada à espectrometria de massas (CG-EM) e por comparação de seus índices de retenção com os de compostos padrões. Tridecano foi o componente majoritário, seguido de quantidades menores e aproximadamente iguais de (E)-4-oxo-2-hexenal e (E)-2-octenal. Também foram identificados (E)-2-hexenal, decano, acetato de (E)-2-hexenila, undecano, (E)-4-oxo-2-octenal, dodecano, acetato de (E)-2-octenila, 1-trideceno, tetradecano e pentadecano.The contents of metathoracic glands of adults of the stink bug Dichelops melacanthus (Hemiptera: Pentatomidae) were analyzed. Compounds were identified by gas chromatography (GC), coupled GC-mass spectrometry and matching retention indices and mass spectra with those of authentic samples. Tridecane was the major component followed by lesser and approximately equal amounts of (E)-4-oxo-2-hexenal and (E)-2-octenal. Other compounds identified include (E)-2-hexenal, decane, (E)-2-hexenyl acetate, undecane, (E)-4-oxo-2-octenal, dodecane, (E)-2-octenyl acetate, 1-tridecene, tetradecane and pentadecane.Keywords: Dichelops melacanthus, defensive compounds, short-chain unsaturated aldehydes, unsaturated acetates, tridecane IntroductionInsects have evolved a multitude of chemical and behavioral defenses against other offensive organisms. Stink bugs, as their name suggests, produce large quantities of strong-smelling and irritating defensive chemicals, which are released when the bugs are disturbed or molested. 1In general, heteropterans produce allomones in dorsal abdominal scent glands as immatures, and in metathoracic scent glands as adults. [1][2][3] Numerous reports attest to the efficacy of the secretions of the metathoracic and abdominal scent glands as effective defenses against predation. 1,2,4 They also may have a role as alarm pheromones, 5 as has been demonstrated for similar types of compounds produced by bug species in other families. 6,7 Stink bug defensive compounds have received considerable study, and it has been shown that the types of compounds constituting the defensive chemical blends typically consist of alkane hydrocarbons and saturated and unsaturated aldehydes and esters. In adults, the defensive compounds are produced in large, well-defined, and usually colored metathoracic glands, which are not present in the immature stages.Sex pheromones have been identified from only a few phytophagous stink bug species to date. 8,9 In all cases reported, components from metathoracic glands have not been part of the pheromone blend. However, because stink bugs readily release defensive compounds when disturbed, it is difficult if not impossible to collect extracts of sex pheromones uncontaminated by these components.The main objective of this study was to characterize the defensive compounds produced in the metathoracic glands o...
The alydid bug parvus (Westwood) is not easily detected in the field and the discovery of attractants may be a suitable way to monitor this species. The attraction of N. parvus to traps (transparent, transparent green and yellow) baited with cow urine and ammonia was studied in two field trials. Traps were placed near a terrace with pigeon pea plants (Cajanus cajan L.). Tap water, NaCl 10% aqueous solution (w/v), cow urine, and ammonia (NH 4 OH 1% aqueous solution) were tested as attractants in yellow, transparent and transparent green traps. Green traps baited with cow urine caught more bugs than yellow and transparent traps (3.2 and 7.2 times more, respectively), and more bugs than traps of the same color with just water (no captures) or NH 4 OH solution (14.5 times more). Traps baited with ammonia caught more bugs than traps with water: 14.4, 4.7 and 6.7 times more than transparent green, yellow, and transparent traps, respectively, or NaCl solution: 3.9, 7.6 and 6.2 times, respectively. Both ammonia and cow urine are attractive to N. parvus and may be tested to monitor the bugs in the field. Key words: semiochemical, attractant, trap color Atração de Neomegalotomus parvus (Westwood) (Heteroptera: alydidae) por urina de vaca e amônia RESUMO: O percevejo alidídeo Neomegalotomus parvus (Westwood) não é facilmente detectado no campo e a descoberta de atraentes pode ser uma forma adequada para monitorar a espécie. A atração de N. parvus a armadilhas (transparentes, verde transparente e amarela) iscadas com urina de vaca e amônia foi estudada em dois experimentos em campo. Armadilhas foram colocadas próximas a um terraço com plantas de feijão-guandu (Cajanus cajan L.). Água corrente, solução aquosa de NaCl 10% (p/v), urina de vaca e amônia (solução aquosa de NH 4 OH 1%) foram testadas como atraentes em armadilhas amarelas, transparentes e transparentes verdes foram utilizadas. Armadilhas verdes iscadas com urina capturaram mais insetos do que armadilhas amarelas e transparentes (3,2 e 7,2 vezes mais, respectivamente), e mais insetos do que armadilhas da mesma cor com apenas água (zero insetos) ou solução de NaCl (14,5 vezes mais). Armadilhas iscadas com amônia capturaram mais insetos do que armadilhas com água: 14,4; 4,7 e 6,7 vezes mais em verde transparente, amarela e transparente, respectivamente, ou solução de NaCl: 3,9; 7,6 e 6,2 vezes, respectivamente. Amônia ou urina de vaca são atrativas para N. parvus e podem ser testadas para monitorar o percevejo no campo. Palavras-chave: semioquímicos, atraente, cor de armadilha
Several synthetic and commercial analogs of 1,4-dimethoxybenzene, a kairomone of
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